Some species of prairie voles form socially monogamous pair bonds following sexual behavior. The pair bonds can be interrupted by injecting chemicals that interfere with oxytocin and vasopressin. The chemicals do not interfere with sexual behavior. The chemicals interfere with the normal activity of oxytocin and vasopressin and thereby prevent the formation of pair bonds. Conversely, injecting chemicals that increase the activity of oxytocin and vasopressin causes social but not necessarily sexual monogamous [] pair bonds to form more easily. Increasing the activity of oxytocin and vasopressin can lead to pair bonding without the need for sexual behavior. Studies have also compared species of prairie voles that form socially monogamous pair bonds versus species of prairie voles that do not form socially monogamous pair bonds. The brains of species that form socially monogamous pair bonds contain more neurons that are more sensitive to oxytocin and vasopressin. (This is because the neurons contain more receptors, or chemical "docking ports," for oxytocin and vasopressin.) The findings of many studies have consistently shown that oxytocin and vasopressin play a critical role in socially monogamous pair bonding in prairie voles. For a better understanding of the findings here is an explanation from the director of the National Institute of Mental Health <ref>http://www.psychologytoday.com/blog/sex-dawn/201007/prairie-vole-companion</ref> "Thomas Insel, director of the National Institute of Mental Health (formerly director of Yerkes Primate Center) and an expert on the prairie vole, says that those in the know have a less exalted view of the prairie vole's monogamy: "They'll sleep with anyone but they'll only sit by their partners." Biologist do not define monogamy the same way as most people. "The average person probably thinks of monogamy as a sexually exclusive relationship. Biologists, however, define the word a little differently. The monogamous animal is one that spends most of its time with one mate but is not entirely faithful, points out Insel. Most monogamous animals will, on occasion, mate with a stranger, he says. In addition, the monogamous male vole often takes a fiercely protective stance when a stranger threatens the nest. Finally, such males often help their mates with child-rearing tasks."" <ref>http://findarticles.com/p/articles/mi_m1200/is_n22_v144/ai_14642472/</ref>

+

Some species of prairie voles form socially monogamous pair bonds following sexual behavior. The pair bonds can be interrupted by injecting chemicals that interfere with oxytocin and vasopressin. The chemicals do not interfere with sexual behavior. The chemicals interfere with the normal activity of oxytocin and vasopressin and thereby prevent the formation of pair bonds. Conversely, injecting chemicals that increase the activity of oxytocin and vasopressin causes social but not necessarily sexual monogamous [] pair bonds to form more easily. Increasing the activity of oxytocin and vasopressin can lead to pair bonding without the need for sexual behavior. Studies have also compared species of prairie voles that form socially monogamous pair bonds versus species of prairie voles that do not form socially monogamous pair bonds. The brains of species that form socially monogamous pair bonds contain more neurons that are more sensitive to oxytocin and vasopressin. (This is because the neurons contain more receptors, or chemical "docking ports," for oxytocin and vasopressin.) The findings of many studies have consistently shown that oxytocin and vasopressin play a critical role in socially monogamous pair bonding in prairie voles. For a better understanding of the findings here is an explanation from the director of the National Institute of Mental Health <ref>http://www.psychologytoday.com/blog/sex-dawn/201007/prairie-vole-companion</ref> "Thomas Insel, director of the National Institute of Mental Health (formerly director of Yerkes Primate Center) and an expert on the prairie vole, says that those in the know have a less exalted view of the prairie vole's monogamy: "They'll sleep with anyone but they'll only sit by their partners." Biologist do not define monogamy the same way as most people. "The average person probably thinks of monogamy as a sexually exclusive relationship. Biologists, however, define the word a little differently. The monogamous animal is one that spends most of its time with one mate but is not entirely faithful, points out Insel. Most monogamous animals will, on occasion, mate with a stranger, he says. In addition, the monogamous male vole often takes a fiercely protective stance when a stranger threatens the nest. Finally, such males often help their mates with child-rearing tasks."" <ref>http://archive.is/20120709040526/findarticles.com/p/articles/mi_m1200/is_n22_v144/ai_14642472/</ref>

Part of the effects of oxytocin and vasopressin may be due to their influence on dopamine in the reward circuits of the brain.<ref name="Young,Wang,2004"/><ref name="Insel,Young,2001"/><ref name="Esch,Stefano,2005">Esch, T. & Stefano, G.B. (2005). The neurobiology of love. Neuroendocrinology Letters, 26, 175–192.</ref><ref name="Aragona,Liu,Curtis,Stephan,Wang,2003">Aragona, B.J., Liu, Y., Curtis, J.T., Stephan, F.K., & Wang, Z. (2003). A critical role for nucleus accumbens dopamine in partner-preference formation in male prairie voles. The Journal of Neuroscience, 23, 3483–3490.</ref>

Part of the effects of oxytocin and vasopressin may be due to their influence on dopamine in the reward circuits of the brain.<ref name="Young,Wang,2004"/><ref name="Insel,Young,2001"/><ref name="Esch,Stefano,2005">Esch, T. & Stefano, G.B. (2005). The neurobiology of love. Neuroendocrinology Letters, 26, 175–192.</ref><ref name="Aragona,Liu,Curtis,Stephan,Wang,2003">Aragona, B.J., Liu, Y., Curtis, J.T., Stephan, F.K., & Wang, Z. (2003). A critical role for nucleus accumbens dopamine in partner-preference formation in male prairie voles. The Journal of Neuroscience, 23, 3483–3490.</ref>

The psychology of sexual monogamy deals with the thoughts, feelings, and behaviors of human beings in sexually monogamous relationships.

Psychological studies of sexual monogamy are sparse. Psychologists tend to be more interested in sexual non-monogamy, especially the causes and consequences of sexual infidelity.[citation needed]

Psychological studies of social monogamy have relied heavily on observations of married couples. These studies have identified several important topics:

Relationship Satisfaction Satisfaction usually declines during the first years of marriage. The decline in satisfaction may represent normal rebound, emotional erosion, and/or motivational erosion.

Relationship Duration Studies of people in long-lasting marriages and studies of married couples in laboratories have identified several factors that contribute to the duration of monogamous relationships.

Attachment Attachment, the need for physical and emotional closeness, plays an important role in many aspects of monogamous relationships. Psychologists and neuroscientists have devoted much research to understanding the processes of attachment.

Contents

Psychologists have spent decades studying marital satisfaction. One of the more interesting and robust findings in Western societies is that satisfaction decreases during the first years of marriage.[1][2][3][4][5][6]

Psychologists have offered three types of explanations for these declines: normal rebound, emotional erosion, and motivational erosion. These are not mutually exclusive explanations. Combinations of all three factors could contribute to declines in marital satisfaction.

The events of falling in love and getting married raise people's feelings of happiness and satisfaction to unusually high levels. It is natural for these feelings of happiness and satisfaction to return to more normal levels over time. In other words, some of the decline
in satisfaction during the first years of marriage may be a normal rebound effect, where unusually high levels of satisfaction return to more ordinary levels of satisfaction.

The word hedonic refers to pleasure or happiness. The basic idea of the hedonic treadmill model is that people have a set level of life satisfaction. Their set levels of life satisfaction are determined by a variety of factors including genes and life experiences. Happy events may temporarily make people more satisfied, and distressing events may temporarily make people less satisfied, but once these events pass, people return to their set levels of satisfaction. The events of falling in love and getting married cause people to report feeling very satisfied at the beginning of their marriages. People subsequently begin to return to their set levels of satisfaction. This causes people to report a decrease in satisfaction. Recent studies have suggested that set points of satisfaction may be easier to change than psychologists originally theorized,[9] although it remains unclear whether or not marriage makes lasting changes to set points of satisfaction.[10][11]

More research needs to be conducted to clarify how the hedonic treadmill contributes to decreases in marital satisfaction.

Another example of a rebound explanation is the self-expansion model.[6]
The self-expansion model has two main ideas:

People are motivated to increase their physical resources, social resources, knowledge, perspectives, and identities.

People achieve this motivation by forming close relationships in which their partner's physical resources, social resources, knowledge, perspectives, and identities are treated to some extent as their own.

When two people fall in love and develop an intimate relationship, they begin to include their partners in their concepts of themselves. People feel like they acquire new capabilities because they have the support of close partners. "I might not be able to handle parenthood by myself, but with the help of my partner's good parenting skills, I'll be a good parent." Several studies have shown that concepts of self and partner begin to overlap in the manner predicted by the self-expansion model.[6][12][13][14][15][16]

According to the self-expansion model, people experience a lot of self-expansion at the beginning of relationships when they constantly learn new things about themselves and their partners. Rapid self-expansion pushes satisfaction to very high levels. However, as the relationship matures, the rate of self-expansion slows, and people experience a relative decline in satisfaction. This may help explain the loss of satisfaction as the marriage matures.

Once couples are married, they have to deal with the inevitability of arguments and conflict. Couples who deal poorly with arguments and conflict build up a history of negative emotional interactions that erodes marital satisfaction.

Karney and Bradbury reviewed a few studies of marital satisfaction and created the vulnerability-stress-adaptation model.[17]
As the name implies, the vulnerability-stress-adaptation model involves three main concepts:

Vulnerability - each partner brings strengths and weaknesses to the relationship, including personality, beliefs and attitudes about marriage, and social background.

Stress - various life events can cause the partners to experience tension and aggravation.

Adaptation - the partners engage in processes to deal with conflict, which vary in terms of how the partners communicate and support each other.

How well couples handle conflict and stress depends on their vulnerabilities, the kinds of stresses they face, and their processes of adaptation. Couples who handle conflict and stress poorly become less and less satisfied with their relationships over time.

Over time couples may feel they have drifted apart. They may no longer share the same relationship goals, and they may no longer support one another in achieving personal goals. This can reduce their motivation for being in the relationship. Loss of motivation for being in the relationship leads to less satisfaction.

Studies have shown that spousal support for goals affects marital satisfaction. One study, for example, distinguished between how much a spouse supports the fulfillment of one's personal goals and how much a spouse supports the fulfillment of mutually shared goals.[18]

The study found each kind of support contributed positively to marital satisfaction. The more support a spouse provides for the fulfillment of personal and shared goals, the more satisfying the marriage. Loss of spousal support emotionally, for goals, may help explain declines in marital satisfaction.

Researchers have recently proposed a motivational model of marital satisfaction. The motivational model of marital satisfaction makes three basic claims:

Each person's motivational style influences his or her intimate relationship behaviors.

The intimate relationship behaviors of both partners influence how couples perceive their adaptive behaviors.

How the couple perceives their adaptive behaviors influences their satisfaction with the marriage.

People have different motivational styles depending on whether behaviors are intrinsically or extrinsically motivated. Intrinsic motivation means the behaviors are chosen and fully endorsed by the person performing them. Extrinsic motivation means the behaviors are coerced or imposed on the person performing them. An initial study of 63 couples has shown that different motivational styles influence relationship behaviors, which in turn influence relationship satisfaction.[19]
Shifts from intrinsic motivation to extrinsic motivation may help explain declines in satisfaction as a marriage matures.

Not everyone agrees the duration of a relationship indicates the success of a relationship. Some reject the idea of "till death do us part" in favor of "as long as love shall last."[20]

Constantine and Constantine have summarized this perspective:

"For our part, to stay together for the longest possible time is a poor goal for marriage. Other ends—growth, fulfillment, happiness, among others—are more important and may demand shorter relationships if they are given priority. People change and the marriage that was valid at one time may lose its validity." (Constantine & Constantine, 1973, page 203)[21]

Whether or not the duration of a relationship indicates the success of a relationship depends on the values of the partners involved. This section does not argue for or against the value of relationship duration. This section merely discusses factors that contribute to longer lasting relationships.

Many psychologists view relationship dissatisfaction as the ultimate factor leading to separation and divorce. Many factors may contribute to relationship satisfaction, but satisfaction ultimately motivates people to remain together or break up. People who are satisfied with their relationships tend to remain together. People who are not satisfied with their relationships tend to separate or divorce. The factors that influence relationship satisfaction, some of which are discussed in the previous section of this article, also contribute to relationship duration.

John Gottman and colleagues use detailed observations of how couples interact to predict whether or not their marriages will last. They can now predict with 81-87 percent accuracy whether or not a particular couple will remain married or get divorced.[22]
Below are some patterns of the partner interactions that predict the duration of marriages.

One pattern that predicts relationship duration is the balance of positive and negative interactions.[23]

Positive interactions can repair damage done by negative interactions. However, negative interactions have a stronger impact than positive interactions, so couples need to engage in far more positive interactions than negative interactions to remain stable. Stable and happy couples consistently engage in at least 5 positive interactions for every 1 negative interaction. Couples who maintain a 5:1 ratio of positive interactions to negative interactions are less likely to break up.

A second pattern that predicts relationship duration is a cascade of destructive interactions. Gottman has identified four destructive interactions which he calls the four horsemen.[24] The four horsemen include:

Criticism — instead of complaining about a behavior, you attack your partner's personality or character, usually with blame. Criticism of personality also comes in the form of listing complaints about past behaviors and thereby suggesting a character fault.

Contempt — contempt is criticism that is intended to insult and psychologically abuse a partner. Contempt reflects a very negative view of your partner. It entails a lack of concern for the partner. Whereas anger is an attempt to fix a problem or convince a person to change, contempt is a total dismissal of any hope that the problem can be fixed.

Defensiveness — defensiveness is a way of avoiding taking responsibility for setting things right by denying responsibility, making excuses, attributing negative thoughts to partners, using one's own complaints to counter a partner's complaints, and simply repeating oneself.

Stonewalling — stonewalling is a break down of communication. The partners turn into 'stone walls' and stop responding to communication.

Gottman sees these four destructive interactions as occurring in a cascade. Criticism leads to contempt; contempt leads to defensiveness; and defensiveness leads to stonewalling. Couples who go through this cascade are more likely to break up.

A third pattern that predicts relationship duration is the use of humor and soothing during arguments. Gottman and colleagues write:

"We conclude that the marriages that wound up happy and stable had a softened start-up by the wife, that the husband accepted influence from her, that he de-escalated low-intensity negative affect, that she was likely to use humor to effectively soothe him, and that he was likely to use positive affect and de-escalation to effectively soothe himself. The alternative to the active listening model suggested by these analyses is a model of gentleness, soothing, and de-escalation of negativity (negativity by one spouse is followed by the partner's neutral affect)."[25][26]

People who use humor and gentleness to soothe the feelings of their partners, and who respond calmly to the negative emotional expressions of their partners, are less likely to break up with their partners.

Studies of people in long-lasting marriages have identified a variety of factors that may contribute to the duration of relationships. Robyn Parker offers a good summary of these studies in an online article called Making Marriages Last
.[27][28] Based on a more technical review of the studies, Parker identifies several tasks that couples must accomplish to increase the chances of lasting marriages:[29]

Separating from the family of origin (parents, brothers, sisters, etc.)

Building togetherness and creating autonomy

Becoming parents

Coping with crisis

Making a safe place for conflict

Exploring sexual love and intimacy

Sharing laughter and keeping interests alive

Providing emotional nurturance

Preserving a double vision

One problem with this type of research is that different researchers identify different factors associated with the duration of marriages. For example, Klagsbrun identified the following key characteristics of marriages lasting 15 years or longer:[30]

Ability to change and adapt to change

Ability to live with the unchangeable

Assumption of permanence (i.e., the marriage will last a lifetime)

Trust

Balance of dependencies (power)

Enjoyment of each other's company

Cherished, shared history

Luck

Compare the lists above to the following list of five factors that Mackey and O'Brien consider critical for lasting marriages:[31]

Containment of one's self in conflict

Mutuality of decision-making

Quality of communication

Relational values of trust, respect, understanding, and equality

Sexual and psychological intimacy

Clearly there are common themes running through the lists described above. Yet, the lists reflect the interests and biases of the researchers, which means the lists should be considered initial findings that need to be confirmed by future studies.

One particularly interesting study asked 351 couples married 15 years or longer to list the main reasons for their marital success.[32]
Even though the spouses answered independently, the wives and the husbands produced identical lists of the top six reasons for their success:

Spouse as best friend

Liking spouse as a person

Marriage as a long term commitment

Agreement on aims and goals

Spouses becoming more interesting to each other

Wanting the relationship to succeed

The high amount of consensus between husbands and wives suggests these factors may indeed play a critical role in the duration of marriages.

Attachment is the tendency to seek closeness to another person, to feel secure when that person is present, and to feel anxious when that person is absent. Many psychologists conceive attachment in terms of attachment theory. Attachment theory makes no specific claims about the neural processes that make attachment possible. Neuroscientists have identified some of the neural processes that contribute to pair bonding in animals, and a few intriguing studies suggest a role for neural processes in human attachment.

Attachment theory, created by John Bowlby and Mary Ainsworth, originally focused on children's desires for closeness with their parents. In 1987, Cindy Hazen and Phillip Shaver extended attachment theory to adult romantic relationships. Research into adult attachment flourished, making attachment theory one of the leading theories for understanding adult romantic relationships. The concept of attachment has been related to a variety of other relationship phenomena including social cognition, satisfaction, affect regulation, support, intimacy, and jealousy.

Studies of pair bonding in animals have allowed scientists to identify several chemicals in the brain related to social monogamy. Three chemicals which have received a lot of attention are oxytocin, vasopressin, and dopamine. These chemicals have been strongly linked to socially monogamous pair bonding in prairie voles.[33][34][35][36]

Some species of prairie voles form socially monogamous pair bonds following sexual behavior. The pair bonds can be interrupted by injecting chemicals that interfere with oxytocin and vasopressin. The chemicals do not interfere with sexual behavior. The chemicals interfere with the normal activity of oxytocin and vasopressin and thereby prevent the formation of pair bonds. Conversely, injecting chemicals that increase the activity of oxytocin and vasopressin causes social but not necessarily sexual monogamous [] pair bonds to form more easily. Increasing the activity of oxytocin and vasopressin can lead to pair bonding without the need for sexual behavior. Studies have also compared species of prairie voles that form socially monogamous pair bonds versus species of prairie voles that do not form socially monogamous pair bonds. The brains of species that form socially monogamous pair bonds contain more neurons that are more sensitive to oxytocin and vasopressin. (This is because the neurons contain more receptors, or chemical "docking ports," for oxytocin and vasopressin.) The findings of many studies have consistently shown that oxytocin and vasopressin play a critical role in socially monogamous pair bonding in prairie voles. For a better understanding of the findings here is an explanation from the director of the National Institute of Mental Health [37] "Thomas Insel, director of the National Institute of Mental Health (formerly director of Yerkes Primate Center) and an expert on the prairie vole, says that those in the know have a less exalted view of the prairie vole's monogamy: "They'll sleep with anyone but they'll only sit by their partners." Biologist do not define monogamy the same way as most people. "The average person probably thinks of monogamy as a sexually exclusive relationship. Biologists, however, define the word a little differently. The monogamous animal is one that spends most of its time with one mate but is not entirely faithful, points out Insel. Most monogamous animals will, on occasion, mate with a stranger, he says. In addition, the monogamous male vole often takes a fiercely protective stance when a stranger threatens the nest. Finally, such males often help their mates with child-rearing tasks."" [38]

Part of the effects of oxytocin and vasopressin may be due to their influence on dopamine in the reward circuits of the brain.[34][35][39][40]

Reward circuits are neurons in the brain responsible for feelings of pleasure and reinforcement in response to positive stimuli such as food, sex, and social interaction. Dopamine is one of the key chemicals that controls the reward circuits of the brain. Oxytocin and vasopressin may influence how dopamine acts on the reward circuits. Thus, oxytocin and vasopressin may facilitate attachment to relationship partners by influencing the activity of dopamine in reward circuits during positive interactions with those partners.

Although human brains contain oxytocin, vasopressin, and dopamine, human brains differ in many respects from animal brains. These differences may include changes in how oxytocin, vasopressin, and dopamine work. Neuroscientists simply do not understand the differences between human brains and animal brains well enough to say these chemicals play a role in human pair bonding. Yet, initial studies look promising. Oxytocin reduces stress in human beings.[39]

Oxytocin may facilitate attachment by reducing stress in response to the support and comfort offered by relationship partners. Oxytocin also increases trust in human beings.[41][42]

Oxytocin may facilitate attachment by increasing trust between relationship partners. Brain scans have shown that areas of the human brain containing oxytocin, vasopressin, and dopamine are activated by looking at pictures of attachment figures but not by looking at pictures of other people.[43][44][45]

The coming decades promise a better understanding of how oxytocin, vasopressin, and dopamine function in human attachment.

Recent studies have looked at which areas of the human brain play a role in attachment.[44][45]

These studies asked people to look at pictures of their romantic partners or pictures of their children. Some areas of the brain were activated by both pictures of romantic partners and pictures of children. These areas of the brain were involved in both romantic and parental attachment. But other areas of the brain were activated only by pictures of romantic partners or only by pictures of children. These areas of the brain appeared to be involved in either romantic attachment or parental attachment, but not both. These findings have opened the door to future studies clarifying how different areas of the brain function in attachment.

At least one police study found that heterosexual women who reported having a current sexual partner spent less time looking at images of members of the opposite sex than women who did not have a current sexual partner. In contrast, the study found that heterosexual men spent equal amounts of times looking at faces regardless of whether or not they had a current sexual partner. The researchers interpreted these results to suggest that "women, on average, are relatively committed in their romantic relationships, 'which possibly suppresses their attention to and appraisal of alternative partners.'"[46]